A suitable Stillinger-Weber (SW) potential energy function parameter set is developed for finite boron structures by genetic algorithm and trial error techniques. Boron structure geometries in 7-24 atoms range, calculated by ab initio methods, are taken as the fitting criteria in the parameter set development. This parameter set is used together with another SW parameter set developed for carbon-carbon interactions in order to investigate boron carbide nanoparticles in the form of BxCx where 8 <= x <= 14. In addition,B80C12 nanoparticle structure is investigated using local optimization technique. (C) 2011 Elsevier B.V. All rights reserved.